单通道高阶调制线性混合信号的频偏估计

摘要

针对具有固定帧长和固定帧同步序列的单通道高阶调制线性混合信号，当两路信号编码异步时，在已知帧长的条件下提出一种基于最大似然准则的频偏估计算法，并给出了算法的有效频偏估计范围。算法通过求互相关获得目标函数，并利用分级搜索的方法估计频偏。为对算法的性能进行评价，文中同时推导了混合信号频偏估计的克拉美罗界（Cramer-Rao Bound ，CRB ）。仿真结果表明，算法在低 Eb／N0下可获得接近CRB的估计性能。此外，算法还适用于功率非对称的混合信号。%For single-channel linear mixture of high-order modulated signals which have the fixed frame length and sync code ,a frequency offset estimation (FOE ) algorithmbased on the maximum likelihood criterion is proposed when the two signals are coded asynchronously ,and the effective range of FOE is given .FOE is calculated byoptimising the objective function ,which is ob-tained from cross-correlation computation ,and the optimised process is accomplished by utilising hierarchical search .To evaluate the performance of the proposed algorithm ,Cramer-Rao Bound (CRB)of mixed-signal FOE is derived .Simulation results show that ,the estimation performance of the algorithm can come close to CRB performance with low Eb/N0 .The proposed algorithm is also ap-plied to the FOE of a mixed signal whose power is asymmetrical .